On Fri, 15 Apr 2011, Dave Hansen wrote:
>
> This originally started as a simple patch to give vmalloc()
> some more verbose output on failure on top of the plain
> page allocator messages. Johannes suggested that it might
> be nicer to lead with the vmalloc() info _before_ the page
> allocator messages.
>
> But, I do think there's a lot of value in what
> __alloc_pages_slowpath() does with its filtering and so
> forth.
>
> This patch creates a new function which other allocators
> can call instead of relying on the internal page allocator
> warnings. It also gives this function private rate-limiting
> which separates it from other printk_ratelimit() users.
>
> Signed-off-by: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
> ---
>
> linux-2.6.git-dave/include/linux/mm.h | 2 +
> linux-2.6.git-dave/mm/page_alloc.c | 63 ++++++++++++++++++++++------------
> 2 files changed, 44 insertions(+), 21 deletions(-)
>
> diff -puN include/linux/mm.h~break-out-alloc-failure-messages include/linux/mm.h
> --- linux-2.6.git/include/linux/mm.h~break-out-alloc-failure-messages 2011-04-15 08:44:06.911445625 -0700
> +++ linux-2.6.git-dave/include/linux/mm.h 2011-04-15 08:45:10.087416551 -0700
> @@ -1365,6 +1365,8 @@ extern void si_meminfo(struct sysinfo *
> extern void si_meminfo_node(struct sysinfo *val, int nid);
> extern int after_bootmem;
>
> +extern void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...);
> +
> extern void setup_per_cpu_pageset(void);
>
> extern void zone_pcp_update(struct zone *zone);
> diff -puN mm/page_alloc.c~break-out-alloc-failure-messages mm/page_alloc.c
> --- linux-2.6.git/mm/page_alloc.c~break-out-alloc-failure-messages 2011-04-15 08:44:06.915445623 -0700
> +++ linux-2.6.git-dave/mm/page_alloc.c 2011-04-15 08:48:34.255321834 -0700
> @@ -54,6 +54,7 @@
> #include <trace/events/kmem.h>
> #include <linux/ftrace_event.h>
> #include <linux/memcontrol.h>
> +#include <linux/ratelimit.h>
>
> #include <asm/tlbflush.h>
> #include <asm/div64.h>
> @@ -1734,6 +1735,46 @@ static inline bool should_suppress_show_
> return ret;
> }
>
> +static DEFINE_RATELIMIT_STATE(nopage_rs,
> + DEFAULT_RATELIMIT_INTERVAL,
> + DEFAULT_RATELIMIT_BURST);
> +
> +void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...)
> +{
> + va_list args;
> + unsigned int filter = SHOW_MEM_FILTER_NODES;
> + const gfp_t wait = gfp_mask & __GFP_WAIT;
> +
"wait" is unnecessary. You didn't do "const gfp_t nowarn = gfp_mask &
__GFP_NOWARN;" for the same reason.
> + if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs))
> + return;
> +
> + /*
> + * This documents exceptions given to allocations in certain
> + * contexts that are allowed to allocate outside current's set
> + * of allowed nodes.
> + */
> + if (!(gfp_mask & __GFP_NOMEMALLOC))
> + if (test_thread_flag(TIF_MEMDIE) ||
> + (current->flags & (PF_MEMALLOC | PF_EXITING)))
> + filter &= ~SHOW_MEM_FILTER_NODES;
> + if (in_interrupt() || !wait)
> + filter &= ~SHOW_MEM_FILTER_NODES;
> +
> + if (fmt) {
> + printk(KERN_WARNING);
> + va_start(args, fmt);
> + vprintk(fmt, args);
> + va_end(args);
> + }
> +
> + printk(KERN_WARNING "%s: page allocation failure: order:%d, mode:0x%x\n",
> + current->comm, order, gfp_mask);
pr_warning()?
current->comm should always be printed with get_task_comm() to avoid
racing with /proc/pid/comm. Since this function can be called potentially
deep in the stack, you may need to serialize this with a
statically-allocated buffer.
> +
> + dump_stack();
> + if (!should_suppress_show_mem())
> + show_mem(filter);
> +}
> +
> static inline int
> should_alloc_retry(gfp_t gfp_mask, unsigned int order,
> unsigned long pages_reclaimed)
> @@ -2176,27 +2217,7 @@ rebalance:
> }
>
> nopage:
> - if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit()) {
> - unsigned int filter = SHOW_MEM_FILTER_NODES;
> -
> - /*
> - * This documents exceptions given to allocations in certain
> - * contexts that are allowed to allocate outside current's set
> - * of allowed nodes.
> - */
> - if (!(gfp_mask & __GFP_NOMEMALLOC))
> - if (test_thread_flag(TIF_MEMDIE) ||
> - (current->flags & (PF_MEMALLOC | PF_EXITING)))
> - filter &= ~SHOW_MEM_FILTER_NODES;
> - if (in_interrupt() || !wait)
> - filter &= ~SHOW_MEM_FILTER_NODES;
> -
> - pr_warning("%s: page allocation failure. order:%d, mode:0x%x\n",
> - current->comm, order, gfp_mask);
> - dump_stack();
> - if (!should_suppress_show_mem())
> - show_mem(filter);
> - }
> + warn_alloc_failed(gfp_mask, order, NULL);
> return page;
> got_pg:
> if (kmemcheck_enabled)
--
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